In the oil and gas industry the volume of storage tanks is calibrated periodically in order to be able to accurately determine the amount of fuel stored in the tank. Typically, a level gauge is used to determine the amount of fuel in a tank. However, storage tanks located in environments subject to high average temperatures tend to expand non-uniformly. The expansions are often difficult to measure accurately and can have an appreciable effect on the total volume. When the volume of a tank changes, the accuracy of standard gauge readings, which are based on a static volume of the tank, diminish. Inaccurate fuel level readings can lead to systematic undervaluation of fuel assets and consequent loss of revenue during custodial transfers.
Increasing the frequency of tank calibration could improve accuracy and yield financial benefits. However, commonly-used calibration techniques typically take an unduly long time to perform, e.g., 3 to 8 hours per tank. These lengthy techniques cause considerable disruption to the operation of the tanks, which can be scheduled for product transfers almost continuously.
What is therefore needed is a calibration technique applicable to large structures such as storage tanks that is both highly accurate and has minimal impact to their operation.